To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the current condition of the coin (70, MBC-) and the hammer prices from previous auctions.

1. Condition: The coin has a condition of 70 (MBC-), indicating that it is in an acceptable state, but not of high quality. This suggests that its price will not reach the highest levels seen in coins of better condition.

2. Previous hammer prices:
- In previous auctions, hammer prices have varied considerably, but we can observe that coins with similar conditions (80 and 85) have reached hammer prices of up to 45 euros.
- The auction with a condition of 100 reached a hammer price of 120 euros, but that is not relevant for our current coin.

3. Average hammer price: The average hammer price for this coin is 50.83 euros, which gives us a good reference.

4. Price trends: Since the coin has sold every time it has been auctioned, and considering that the average starting price is 32.57 euros, we can infer that there is a consistent interest in this coin.

Based on these points, an estimated maximum purchase price for the coin with a condition of 70 could be in the range of 40 to 60 euros, considering that the average hammer price is 50.83 euros and that the condition is not the best.

Therefore, a reasonable estimated maximum purchase price could be 60 euros.